In piping equipment or the like in which high-pressure fluid such as hydrogen flows, a trunnion-type ball valve for high pressure is used to reliably prevent leakage of the high-pressure fluid. The ball valve of this type is normally provided to a structure in which a ball valve body is supported in a rotatable body via a stem and a trunnion, a ball seat is attached inside the body as being in a state of being held by a retainer member, and this ball seat is attached in a close-contact state to the ball valve body via the retainer member and via a spring force of a spring. Here, a portion between the retainer member and the body is sealed by an O ring for sealing.
As a ball valve for high-pressure fluid as described above, a trunnion-type ball valve for high pressure of PTL 1 is disclosed. This ball valve is suitable particularly for a valve for a hydrogen station for a fuel-cell vehicle and, in view of the purpose of keeping hermeticity of a valve seat with respect to high-pressure hydrogen over a long period of time to ensure durability, is provided to a structure in which a metal-made ball seat, that is, a metal seat, is attached for sealing with a ball.
On the other hand, as another technique for improving valve seat sealability of a ball valve, a ball valve of PTL 2 is disclosed. In this ball valve, a resin-made ball seat, that is, a soft seat, is provided for sealing with a ball. In this case, the structure is such that the resin-made ball seat is fixed to a seat retainer and is pressed by a spring to a ball side.
In these ball valves for high-pressure fluid, it is required to improve hermeticity while ensuring slidability between the ball and the seat side.
These ball valves are used as a shutoff valve in a dispenser in, for example, a hydrogen station described in PTL 3. The shutoff valve is connected via a connection hose to a filling nozzle as a region of filling a vehicle with hydrogen and is provided so that, with this shutoff valve being opened and closed, hydrogen is supplied to a hydrogen tank of the vehicle via the connection hose and the filling nozzle.